Selectable Filters for a Visual Prosthesis

ABSTRACT

The present invention is a visual prosthesis including a visor with an embedded camera and changeable optical filters to limit light entering the lens of the camera. This invention will allow use of custom filters to limit light intensity or certain light frequencies sent to the camera of the visual prosthesis in a variety of brightness conditions which will remove glare. It will allow modification of the color of the light sent to camera of the visual prosthesis to respond to different environments. Users may choose the best filter to suit their needs in real time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Ser. No. 61/330,098for “Selectable Filter for a Visual Prosthesis” filed on Apr. 30, 2010,and is related to U.S. patent application Ser. No. 11/893,260, filedAug. 15, 2007 for “Visor for a Visual Prosthesis, published as2008/0154336, both of which are incorporated herein by reference intheir entirety.

GOVERNMENT RIGHTS NOTICE

This invention was made with government support under grant No.R24EY12893-01, awarded by the National Institutes of Health. Thegovernment has certain rights in the invention.

FIELD

The present disclosure is generally directed to neural stimulation andmore specifically to a visual prosthetic apparatus for retinalstimulation.

BACKGROUND

As intraocular surgical techniques have advanced, it has become possibleto apply stimulation on small groups and even on individual retinalcells to generate focused phosphenes through devices implanted withinthe eye itself. This has sparked renewed interest in developing methodsand apparatuses to aid the visually impaired. Specifically, great efforthas been expended in the area of intraocular retinal prosthesis devicesin an effort to restore vision in cases where blindness is caused byphotoreceptor degenerative retinal diseases such as retinitis pigmentosaand age related macular degeneration which affect millions of peopleworldwide.

Neural tissue can be artificially stimulated and activated by prostheticdevices that pass pulses of electrical current through electrodes onsuch a device. The passage of current causes changes in electricalpotentials across visual neuronal membranes, which can initiate visualneuron action potentials, which are the means of information transfer inthe nervous system.

Based on this mechanism, it is possible to input information into thenervous system by coding the information as a sequence of electricalpulses which are relayed to the nervous system via the prostheticdevice. In this way, it is possible to provide artificial sensationsincluding vision.

One typical application of neural tissue stimulation is in therehabilitation of the blind. Some forms of blindness involve selectiveloss of the light sensitive transducers of the retina. Other retinalneurons remain viable, however, and may be activated in the mannerdescribed above by placement of a prosthetic electrode device on theinner (toward the vitreous) retinal surface (epiretinal). This placementmust be mechanically stable, minimize the distance between the deviceelectrodes and the visual neurons, and avoid undue compression of thevisual neurons.

In 1986, Bullara (U.S. Pat. No. 4,573,481) patented an electrodeassembly for surgical implantation on a nerve. The matrix was siliconewith embedded iridium electrodes. The assembly fit around a nerve tostimulate it.

Dawson and Radtke stimulated cat's retina by direct electricalstimulation of the retinal ganglion cell layer. These experimentersplaced nine and then fourteen electrodes upon the inner retinal layer(i.e., primarily the ganglion cell layer) of two cats. Their experimentssuggested that electrical stimulation of the retina with 30 to 100 uAcurrent resulted in visual cortical responses. These experiments werecarried out with needle-shaped electrodes that penetrated the surface ofthe retina (see also U.S. Pat. No. 4,628,933 to Michelson).

The Michelson '933 apparatus includes an array of photosensitive deviceson its surface that are connected to a plurality of electrodespositioned on the opposite surface of the device to stimulate theretina. These electrodes are disposed to form an array similar to a “bedof nails” having conductors which impinge directly on the retina tostimulate the retinal cells. U.S. Pat. No. 4,837,049 to Byers describesspike electrodes for neural stimulation. Each spike electrode piercesneural tissue for better electrical contact. U.S. Pat. No. 5,215,088 toNorman describes an array of spike electrodes for cortical stimulation.Each spike pierces cortical tissue for better electrical contact.

The art of implanting an intraocular prosthetic device to electricallystimulate the retina was advanced with the introduction of retinal tacksin retinal surgery. De Juan, et al. at Duke University Eye Centerinserted retinal tacks into retinas in an effort to reattach retinasthat had detached from the underlying choroid, which is the source ofblood supply for the outer retina and thus the photoreceptors. See,e.g., de Juan, et al., 99 Am. J. Ophthalmol. 272 (1985). These retinaltacks have proved to be biocompatible and remain embedded in the retina,with the choroid/sclera, effectively pinning the retina against thechoroid and the posterior aspects of the globe. Retinal tacks are oneway to attach a retinal array to the retina. U.S. Pat. No. 5,109,844 tode Juan describes a flat electrode array placed against the retina forvisual stimulation. U.S. Pat. No. 5,935,155 to Humayun describes aretinal prosthesis for use with the flat retinal array described in deJuan.

Off the shelf miniature cameras used in visual prostheses, or othercommon miniaturized cameras suitable for mounting in a pair of glasses,have difficulty responding to high intensity lighting conditions anddifferent cameras can have different color responses, which is notideal. Electronic compensation is not possible in some cases where thecamera is saturated. Further electronic compensation requires processingtime that can be better allocated to other visual prosthesis functions.

SUMMARY

The present invention is a visual prosthesis including a visor with anembedded camera and changeable optical filters to limit light enteringthe lens of the camera. This invention will allow use of custom filtersto limit light intensity or certain light frequencies sent to the cameraof the visual prosthesis in a variety of brightness conditions whichwill remove glare. It will allow modification of the color of the lightsent to camera of the visual prosthesis to respond to differentenvironments. Users may choose the best filter to suit their needs inreal time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the visor of the preferred visualprosthesis.

FIGS. 2 and 3 show perspective views of the preferred visor of a visualprosthetic apparatus.

FIG. 4 is a shade wheel for an alternative embodiment.

FIG. 5 is the alternative visor using a shade wheel.

FIG. 6 shows a perspective view of the implantable portion of the visualprosthesis.

FIG. 7 is a side view of the implantable portion of the visualprosthesis.

DETAILED DESCRIPTION

The glasses or visor 1 may have a sliding lens cover 7 that can beplaced in front of the camera 3 lens on the visor 1 as shown in FIG. 1.The camera may be mounted in the bridge of the glasses. The sliding lenscover 7 may be made of dark shade transparent material to limit theintensity of light falling on the camera 3 lens. Based on the ambientlight conditions, the user can utilize this feature to limit brightlight. The sliding cover 7 material may provide a choice of ND (NormalDensity), Graded Neutral Density, normal density plus ultraviolet(ND+UV), Color filters, high contrast filters, or there filters as arecommonly known for use for eye glasses. Desired available filters can becombined into a single lens cover and placed linearly side by side.Incorporating a longer sliding travel, each section of filter can comein front of the lens for desired effect.

FIGS. 2 and 3 show two different perspective views of an externalportion of a visual prosthetic apparatus according to the presentdisclosure. ‘External’ is here meant to indicate that the portion isexternal to the human body, and not implanted therein. The externalportion includes the visor 1 and is adapted to be used in combinationwith an implantable portion 23, shown in FIGS. 6 and 7. Turning to FIGS.2 and 3, the external portion 1 comprises a frame 2 holding a camera 3,an external coil arrangement 4 and a mounting system 5 for the externalcoil arrangement 4. The external coil arrangement 4 comprises externaltransmitting and receiving radio-frequency (RF) coils adapted to be usedtogether and communicate with an internal RF coil (later shown in FIGS.6 and 7). The mounting system 5 also encloses the RF circuitry formodulating, demodulating, transmitting, and receiving an RF signal.External coil arrangement 4 and mounting system 5 are connected by aflexible connector 6.

Alternatively the filter lens cover can be hinged from the top of theframe and flipped down when needed (not shown). Alternatively the lensmay be hinged to the side of the camera and flipped sideway when needed(also not shown). Referring to FIGS. 4 and 5, alternatively the filterscan be arranged on a composite circular lens cover in pie chart segmentas shown in FIG. 4. FIG. 5 shows the composite circular lens cover 8 infront of the camera 4 lens. The composite circular lens cover 8 isattached to a bearing at its center and mounted to glasses. The rotatingcircular lens cover 8 will allow the desired filter section to be placedin front of the camera 3 lens. Another Alternate embodiment is tointegrate the actual lens cover mounted into the glasses frame so thatit is not visible from the front. The integration can be applicable forboth linear travel lens cover (FIG. 1) as well as rotating lens cover(FIG. 5).

FIG. 6 shows a perspective view of an implantable portion 23 of aretinal prosthesis as disclosed. An electrode array 24 is mounted by aretinal tack or similar means to the epiretinal surface. The electrodearray 24 is electrically coupled by a cable 25, which can pierce thesclera and be electrically coupled to an electronics package 26 externalto the sclera. Electronic package 26 includes the RF receiver andelectrode drivers.

The electronics package 26 can be electrically coupled to the secondaryinductive coil 27. In one aspect, the secondary inductive coil 27 ismade from wound wire. Alternatively, the secondary inductive coil may bemade from a thin film polymer sandwich with wire traces depositedbetween layers of thin film polymer. The secondary coil receives powerand data from the primary coil 4 which is external to the body. Theelectronics package 26 and secondary inductive coil 27 are held togetherby a molded body 28. The molded body 28 may also include suture tabs 29.The molded body narrows in a fan tail 31 to form a strap 30 whichsurrounds the sclera and holds the molded body 28, secondary inductivecoil 27, and electronics package 26 in place. The molded body 28, suturetabs 29 and strap 30 are preferably an integrated unit made of siliconeelastomer. Silicone elastomer can be formed in a pre-curved shape tomatch the curvature of a typical sclera. Furthermore, silicone remainsflexible enough to accommodate implantation and to adapt to variationsin the curvature of an individual sclera. In one aspect, the secondaryinductive coil 27 and molded body 28 are oval shaped, and in this way, astrap 30 can better support the oval shaped coil.

The entire implantable portion 23 is attached to and supported by thesclera of a subject. The eye moves constantly. The eye moves to scan ascene and also has a jitter motion to prevent image stabilization. Eventhough such motion is useless in the blind, it often continues longafter a person has lost their sight. By placing the device under therectus muscles with the electronics package in an area of fatty tissuebetween the rectus muscles, eye motion does not cause any flexing whichmight fatigue, and eventually damage, the device.

FIG. 7 shows a side view of the implantable portion of the retinalprosthesis, in particular, emphasizing the fan tail 31. When the retinalprosthesis is implanted, the strap 30 has to be passed under the eyemuscles to surround the sclera. The secondary inductive coil 27 andmolded body 28 should also follow the strap under the lateral rectusmuscle on the side of the sclera. The implantable portion 23 of theretinal prosthesis is very delicate. It is easy to tear the molded body28 or break wires in the secondary inductive coil 27. In order to allowthe molded body 28 to slide smoothly under the lateral rectus muscle,the molded body is shaped in the form of a fan tail 31 on the endopposite the electronics package 26. Element 32 shows a retentionsleeve, while elements 33 and 34 show holes for surgical positioning anda ramp for surgical positioning, respectively.

In summary, a visual prosthetic apparatus is provided. The apparatusprovides a means for adjusting the light received by the camera. Whilethe invention has been described by means of specific embodiments andapplications thereof, it is understood that numerous modifications andvariations could be made thereto by those skilled in the art withoutdeparting from the spirit and scope of the invention. It is therefore tobe understood that within the scope of the claims, the invention may bepracticed otherwise than as specifically described herein.

1. A visual prosthetic apparatus comprising: an implantable portion andan external portion, wherein the implantable portion comprises an datareceiver, and an array of electrodes, wherein the external portioncomprises a frame, a camera having a lens mounted on the frame and atransmitter sending visual data to the implanted portion, and a movablelens cover to affect the light entering the lens of the camera.
 2. Thevisual prosthetic apparatus according to claim 1, wherein the lens coveris movable in a linear direction.
 3. The visual prosthetic apparatusaccording to claim 1, wherein the lens cover is movable in a circulardirections.
 4. The visual prosthetic apparatus according to claim 1,wherein the lens cover is attached to the frame by a hinge.
 5. Thevisual prosthetic apparatus according to claim 1, wherein the lens coverincludes a normal density filter.
 6. The visual prosthetic apparatusaccording to claim 1, wherein the lens cover includes a Graded NeutralDensity filter.
 7. The visual prosthetic apparatus according to claim 1,wherein the lens cover includes an ultraviolet light filter.
 8. Thevisual prosthetic apparatus according to claim 1, wherein the lens coverincludes a color filter.
 9. The visual prosthetic apparatus according toclaim 2, wherein the lens cover has multiple filters selectable bymovement of the lens cover relative to the frame.
 10. The visualprosthetic apparatus according to claim 3, wherein the lens cover hasmultiple filters selectable by movement of the lens cover relative tothe frame.
 11. A visual prosthetic apparatus for retinal stimulationcomprising: an implantable portion and an external portion, wherein theimplantable portion comprises an RF receiver, an internal coil, and anarray of electrodes, wherein the external portion comprises a frame, acamera having a lens mounted on the frame and an external coil mountedon the frame, and a movable lens cover to affect the light entering thelens of the camera.
 12. The visual prosthetic apparatus according toclaim 11, wherein the lens cover is movable in a linear direction. 13.The visual prosthetic apparatus according to claim 11, wherein the lenscover is movable in a circular directions.
 14. The visual prostheticapparatus according to claim 11, wherein the lens cover is attached tothe frame by a hinge.
 15. The visual prosthetic apparatus according toclaim 11, wherein the lens cover includes a normal density filter. 16.The visual prosthetic apparatus according to claim 11, wherein the lenscover includes a Graded Neutral Density filter.
 17. The visualprosthetic apparatus according to claim 11, wherein the lens coverincludes an ultraviolet light filter.
 18. The visual prostheticapparatus according to claim 11, wherein the lens cover includes a colorfilter.
 19. The visual prosthetic apparatus according to claim 12,wherein the lens cover has multiple filters selectable by movement ofthe lens cover relative to the frame.
 20. The visual prostheticapparatus according to claim 13, wherein the lens cover has multiplefilters selectable by movement of the lens cover relative to the frame.